1. Technical Field
The present invention relates to a piezoelectric resonator used for a small sized electronic apparatus and a method for manufacturing the same.
2. Related Art
The small sized electronic apparatus has been required to be miniaturized further. It is demanded that the piezoelectric resonator becomes smaller which is used for the small sized electronic apparatus.
Here, a resonator element included in the piezoelectric resonator is necessary to have a vibration area as large as possible, because the larger the vibration area is, the smaller the crystal impedance is, allowing the resonator element to vibrate well. Therefore, it is necessary for the resonator element to be contained in a package reduced in size in order to miniaturize the piezoelectric resonator, securing the vibration area of the resonator element. There is a need for an arrangement of an electrode provided in the package to be improved in order to miniaturize the package.
For the reason above, the following approaches have been made, for example. Specifically, an excitation electrode provided to the resonator element on an opposite surface thereof is extracted compactly to miniaturize the package. At the same time, two excitation electrodes as connection electrodes are collected on one surface of the package so as to be connected to a substrate mounting the package with as small area as possible.
As an example of the approaches, there has been known that the resonator substrate provided with the resonator element has a through-hole formed thereon through which is extracted to one surface of the substrate an excitation electrode provided on the other surface, so that two excitation electrodes is collected on one surface of the package (refer to an example of related art listed below, for example).
JP-2002-76826 is an example of related art (paragraphs 0012 to 0014 in page 3, FIGS. 2 to 4).
If the through-hole is provided, the resonator substrate needs an area to be formed with the through-hole. As a result, the resonator substrate with the through-hole is larger than that with no through-hole even if containing the same sized resonator element. Thus, miniaturization of the piezoelectric resonator is restricted to some degree.